Probe by molecular hybridization of human neoplastic tissues for evidence of oncogenic RNA viruses; search for evidence of oncogeniv RNA viruses in "normal" and pathological human biological fluids and tissues by biochemical techniques; attempt purification and characterization of RNA-instructed DNA polymerase enzymes from oncogenic RNA Viruses and human neoplastic tissues; improve current and design new biochemical techniques for the detection and quantitation of RNA tumor viruses; study possible interactions between DNA and RNA tumor viruses in both animal and human cancers; search plasma for viral antigens as systemic diagnostic indicators of presence of tumor.